A novel impedance multiplier-based type-II compensation circuit design for a current-mode DC/DC buck converter

DC/DC converters are fundamental power electronics circuits used to transform a constant direct current (DC) voltage to a different level. In particular, buck converters are widely employed in various electronic systems that require low output voltages. These converters offer advantages such as high efficiency, low noise, and precise output voltage regulation. However, the compensation circuits used in buck converters face design challenges, including large chip area and high cost, due to the integration of high-value passive components on-chip. In this thesis, a novel capacitance multiplier circuit is proposed as a replacement for high-value capacitors in the compensation circuits of buck converters. The proposed circuit is developed based on the impedance multiplier model, providing an extended structure that can function not only as a capacitance multiplier but also as a resistance and inductance multiplier. The circuit features an electronically controllable design and offers flexibility through a floating configuration. The proposed circuit has been designed using 0.18µm TSMC CMOS technology and validated through time-domain and frequency-domain simulations in LTspice. For experimental verification, a prototype of the circuit was implemented using the OPA861 OTA integrated circuit. Additionally, the layout design of the circuit was completed using the ELECTRIC VLSI software. The performance of the proposed capacitance multiplier circuit was compared with existing capacitance multiplier circuits in the literature, demonstrating that it achieves similar electrical performance while occupying a smaller chip area. Monte Carlo and PVT analyses have shown that the circuit exhibits high stability against variations in process parameters, supply voltage, and temperature.